Carbohydrate epitopes in glycoprotein from the opportunistic fungal pathogen Scedosporium apiospermum

Hot aqueous extraction of Scedosporium apiospermum mycelium provided glycoprotein (HET-PR-Sa) containing 37% protein and Rha, Rib, Ara, Man, Gal, Glc, and GlcNH2 in a 26:14:17:22:10:5:6 molar ratio. HPSEC showed a mixture. HET-PR-Sa, on reductive, alkaline β-elimination at 25 °C, gave nonreducing oligosaccharide epitopes (OLIGO-Sa) from O-linked protein and a polymer (HET-PR-Sa-de-O), which was then β-eliminated at 100 °C to give polysaccharide (HET-Sa). The structure of each fraction (methylation, NMR, and ESI-MS analysis) differed from those of a peptidoglycan (PRM-Pb) from mycelium of related, opportunistic pathogen, Pseudallescheria boydii. The predominant nonreducing oligosaccharide formed on β-elimination of PRM-Pb was hexasaccharide 3, whereas those (OLIGO-Sa) from HET-PR-Sa were tetra- 2 and mixed pentasaccharides. Trisaccharide 1 was also identified and is a conserved structure in both fungi. Structural differences confirmed that S. apiospermum is not an anamorph of a P. boydii teleomorph.